Abstract

Regeneration is a precise process that requires regulated cell proliferation and accurate cell fate decisions. The mechanisms that temporally and spatially control the activation or repression of important genes during regeneration are not fully understood. Epigenetic modification of regeneration genes by Polycomb group and Trithorax group chromatin regulators could be key factors that govern gene repression and activation in damaged tissue. Here we report a genetic screen of chromatin regulators that identified phenotypes for many PcG and TrxG mutants and RNAi lines in Drosophila imaginal wing disc regeneration. Furthermore, we show that the two Drosophila SWI/SNF chromatin-remodeling complexes, BAP and PBAP, play distinct roles in regeneration. The PBAP complex regulates regenerative growth and developmental timing, and is required for the expression of JNK signaling targets and upregulation of the growth promoter myc. By contrast, the BAP complex is required for ensuring proper patterning and cell fate by stabilizing expression of the posterior gene engrailed. The core complex components are required for both processes: a weak knockdown of brahma (brm), which encodes the only ATPase of the SWI/SNF complexes, induces the BAP mutant regeneration phenotype, whereas a strong brm mutant shows the PBAP regeneration phenotype. Thus, both SWI/SNF complexes are essential for proper gene expression during tissue regeneration, but play distinct roles in regulating growth and cell fate.

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